It's not the script for the upcoming 2015 Batman and Superman movie, which is being written by David S. Goyer. No, it's a script for Batman Vs. Superman Asylum, which was a movie Warner Bros. was considering to reboot Batman way back in 2002. It's written by Andrew Kevin Walker. ComicBookMovie.com unearthed the script, which can be read on Scribd.com.
Even though the film never got made, it's an interesting read, especially the ending. On the final page, Batman asks Superman, "So, you want to get a beer?" To which Superman answers, "Maybe a soda or something." And Batman snaps back, "Oh my God, what is with you?" We can totally hear Ben Affleck delivering that last line.